Combine 3.5 miles of trail running, 12 miles of mountain biking, two miles of canoeing, “mystery events” and 139 (crazy? courageous?) participants. What do you get? The Rock Dallas Adventure Race, held Saturday at the Murrell Heritage Primitive Camping Area on Lake Grapevine.

Todd Newton competes in the mountain biking leg of the Rock Dallas Adventure Race on Saturday at the Murrell Heritage Primitive Camping Area on Lake Grapevine.

Doug Ummel competes in the Rock Dallas Adventure Race.

Kristen Codish competes in the mountain biking leg of the race.

John Erway competes in the Rock Dallas Adventure Race on Saturday.

Natalie Contorno, left, and Angelo Del Vecchio get their kayak in the water for that portion of the the Rock Dallas Adventure Race on Saturday at the Murrell Heritage Primitive Camping Area on Lake Grapevine.

Competitors in the Rock Dallas Adventure Race begin the event on Saturday at the Murrell Heritage Primitive Camping Area on Lake Grapevine.

James Bielamowicz, left, and Clayton P. Perriraz compete in the race. Competitors could enter solo or as two-person teams.

Chance Barthold gets ready to start the kayaking leg of the race.

Ed Mazur competes in the Rock Dallas Adventure Race.

Competitors in the Rock Dallas Adventure Race paddle their kayaks at the Murrell Heritage Primitive Camping Area on Lake Grapevine.

Paul Fontenot, left, and Kaitlin Kammerer compete in the Rock Dallas Adventure Race on Saturday at the Murrell Heritage Primitive Camping Area on Lake Grapevine. Competitors could enter as two-person teams or solo.

Doug Ummel, left, and Kristen Codish compete in the race.

Jeff Sober competes in the race Saturday at the Murrell Heritage Primitive Camping Area on Lake Grapevine.

Tim Adcock competes in the race.

Melissa White sheds her life preserver during the Rock Dallas Adventure Race on Saturday.

Thomas Mullins competes in the race.

James Bielamowicz competes in the Rock Dallas Adventure Race on Saturday.

Josh Tschuor competesin the race.

Clayton P. Perriraz competes in the Rock Dallas Adventure Race on Saturday at the Murrell Heritage Primitive Camping Area on Lake Grapevine.

Eric Hall competes in the race.

Trevor Parks competes in the race.

Elvira Hall and other competitors ran on the trail during thee Rock Dallas Adventure Race on Saturday at the Murrell Heritage Primitive Camping Area on Lake Grapevine.